scholarly journals Cellular automata simulation for high temperature austenite grain growth based on thermal activation theory and curvature-driven mechanism

2016 ◽  
Vol 94 (12) ◽  
pp. 1353-1364 ◽  
Author(s):  
Min Wang ◽  
Yajun Yin ◽  
Jianxin Zhou ◽  
Hai Nan ◽  
Tong Wang ◽  
...  

Based on the thermal activation theory and curvature-driven mechanism, a 2D cellular automaton model with different state transition rules was built. Validity of the model was proved by the shrinking of circular grains. Grain growth of high temperature austenite was simulated by this model; the morphology, grain size distribution, topological aspects, and local kinetics of austenite grain growth were analyzed under different simulation time. Among the grains with different sides, the 6-sided grains are the most common and 5-sided grains are the second most common. The grains with more than six sides will grow and grains with less than six sides will shrink, while the 6-sided grains will neither grow nor shrink. The kinetics of normal grain growth follows the Burke equation and the growth exponent at different temperatures and activation energies has been researched.

2011 ◽  
Vol 12 (3) ◽  
pp. 171-176 ◽  
Author(s):  
Ying-li Zhao ◽  
Jie Shi ◽  
Wen-quan Cao ◽  
Mao-qiu Wang ◽  
Gang Xie

2011 ◽  
Vol 66-68 ◽  
pp. 108-113 ◽  
Author(s):  
Chang Jiang Song ◽  
Liang Zhu ◽  
Yuan Yi Guo ◽  
Ke Feng Li ◽  
Feng Mei Sun ◽  
...  

By using a thermal simulator this work investigated grain growth behaviour of a Ti+Nb stabilized 12%Cr ferritic stainless steel at high temperature. The results showed that the grain growth rate was less than 1.8μm/s at the temperature of 1200°C, but it suddenly became very high and reached about 50μm/s when the temperature was 1250°C. Analysis results indicate that grain growth of this steel is affected by the small particles on the grain boundaries, and grain growth exponent is about 3.3. Moreover, the activation energy of the grain growth is when the temperature is above 1250°C. Compared with a 27Cr ferritic stainless steel containing only 0.14%Nb, the grain growth exponent of this steel is greater, and grain initial rapid growth temperature is higher.


Author(s):  
V. A. Lutsenko ◽  
T. N. Golubenko ◽  
O. V. Lutsenko ◽  
N. A. Glazunova

The impact of the austenite grain growth of chromo-molybdenum steel on the kinetics of structural decomposition under continuous cooling was studied. It is shown that when the grain is enlarged with an increase in the austenitization temperature from 850 till 1050 °C, the stability of the supercooled austenite in the structure of the chromo-molybdenum steel during the decay process by the intermediate and shear mechanism increases, which contributes to a decrease in the critical quenching rate.


2012 ◽  
Vol 452-453 ◽  
pp. 401-406 ◽  
Author(s):  
Piotr Kula ◽  
Robert Pietrasik ◽  
Konrad Dybowski ◽  
Sylwester Paweta ◽  
Emilia Wołowiec

The variety of vacuum carburizing with prenitriding (PreNitLPC® technology) consists in metering ammonia in the stage of charge heating for carburizing to reduce grain growth in the surface layer of carburized steel. This paper presents the effect of nitrogen interaction on the reduction of austenite grain growth during vacuum carburizing and on the mechanical properties (fatigue strength, impact resistance) of the layer treated in this way in relation to conventional carburizing methods.


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